You have to configure the conditions you want to wait
for (data on file, timeout...) using expect. When the configuration is done, you start waiting
using wait. Then this object is queryable, that means that you can query the state of the
events, using event_occurred.

Always False in boost mode. Exported to {ANY} only
because the language requires it.

CAVEAT: Use only in require/ensure clauses. It's very important. In boost mode, it will
always be False. It's meant to catch programming mistakes, not as a guard. If you feel the need to
call that feature, please check your algorithm. Twice. And don't use it.

Tip: only call event_occurred on events that passed to expect (I mean, the same object,
not a twin!)